How to make a player follow the cursor?
I would not remove the "target" object. Just let it there. You need just one. 

You can activate/deactivate the steering (rather then adding/removing the target object).

To do this you need to sense the events when to do what.

Unfortunately you did not say what you want to get. You just mention what other games are doing.


  "player to cursor" motion where the player travels to cursor when right-click mouse is pressed and stop travelling when not


right mouse button sensor -&gt; AND -&gt; steering actuator


This activates the steering on when pressing the right mouse button, and deactivates the steering when releasing the button.

You also need to think about when to place the target object at the hit position under the cursor. Typically you do that once at right mouse button. 

You can continuously do that while holding the right mouse button too (be aware the situation when the cursor is over a non-targetable position).